PUBLICATION 8115
Patch Budding: A Convenient
Method for Top-Working Olives
WILLIAM H. KRUEGER, Farm Advisor, University of California Cooperative Extension Glenn
County; ZACHARY HEATH, and DOMINIC DELEONARDIS
Occasionally it may be desirable to change the variety of olive growing on an existUNIVERSITY OF
CALIFORNIA
Division of Agriculture
and Natural Resources
http://anrcatalog.ucdavis.edu
ing tree. This can be accomplished by top-working the existing tree (the “rootstock”)
to add the desired variety. Top-working has traditionally been done in California
using the bark graft method, in which scion sticks are inserted into the cambial area
between the bark and the wood of the rootstock (see Olive Production Manual, UC
ANR Publication 3353; see also Propagation of Temperate-Zone Fruit Plants, UC ANR
Publication 21103). The T-bud method of budding commonly used in other tree
crops, while faster than patch budding, often results in bud failure in olives, possibly
because the rootstock overgrows the buds. Additionally, T-budding is not suitable for
larger limbs.
Patch budding can be used for top-working olives alone or in conjunction with
bark grafting. In patch budding, a bark patch containing at least one dormant bud
from the desired scion variety is secured to the cambium of the rootstock where a
matching bark patch has been removed. Patch budding can be more desirable than
bark grafting because
• Less scion material is required.
• It is faster and less expensive.
• It can be done during a longer time period.
• No tree seal is required.
• Damage from wood-boring insects is reduced.
The disadvantage of patch budding is that when it is done on larger limbs, vigorous new growth from patched buds may be more likely to break off.
TIMING
As with bark grafting, patch budding must be done when the bark “slips,” or separates easily from the wood. Depending on seasonal climatic variation and limb size
and position, olive bark should slip from the middle of March to the first of April
until the end of August or September. The bark of smaller-diameter wood usually
slips for a longer period than the bark of
large scaffold limbs. The bark of vigorous
small-diameter shoots may continue to
slip into October and November.
However, the slower growth rate at this
time of year results in slower callus formation and poor bud take. For best
results, patch budding should be completed by the end of August.
SCION WOOD SELECTION
Select vigorous 1- to 2-year-old growth
about the diameter of a pencil or larger to
supply buds for patch budding (fig. 1). If
Figure 1. For best results when patch budding
olives, select bud wood that is about the size of a
pencil. Photo: Zachary Heath.
2
ANR Publication 8115
buds will be patched onto large limbs, take the buds from large scion wood. Remove
the leaves without damaging the buds. Place the bud wood on the rootstock as soon
after collection as possible to prevent it from drying out. If longer storage is necessary,
keep it in a bucket of water in the shade or in plastic bags in an ice chest.
PAT C H B U D D I N G S M A L L T R E E S O R L I M B S
When patch budding small trees or limbs, 3⁄8 inch to 3 inches (1 to 7.5 cm) in diameter, be careful not to remove too much bark from the rootstock when placing the
patches. After removing patches, there should be a strip of bark on the rootstock at
least 1⁄8 inch (3 mm) wide to prevent the rootstock from being girdled. Cut the patches using a double-bladed budding knife with blades 3⁄4 to 11⁄4 (19 to 32 mm) apart. A
double-bladed knife can be made with two razor blades (see Propagation of TemperateZone Fruit Plants, UC ANR Publication 21103, pp. 21–22). The cuts can also be made
with a single-bladed knife. To remove the patches, cut the bark of the scion above and
below the two buds at the node. Using two buds as opposed to
splitting the patch and using only one bud increases the chances
of at least one bud growing successfully. Make a vertical cut
between the two buds and slip the patch sideways to remove it
from the scion (fig. 2). This prevents the buds from remaining
attached to the scion wood. If bud wood is scarce or the rootstock shoot being budded is too small to accommodate the
patch while leaving a strip of the original bark, cut the patch in
half to make two smaller patches with a single bud in each.
Using the double-bladed knife, make two horizontal cuts
on the rootstock, then make a vertical cut at one end of the horizontal cuts. Peel back the bark and slip the bud into place
(fig. 3). Tear the bark even with the second vertical edge of the
bud. The patch should fit snugly on the top and bottom. A
small open space can be left along one side to keep the patch
from buckling and losing cambial contact as the tree grows.
Alternatively, one edge of the patch can be tucked under the
Figure 2. Remove the bud by slipping it sideways from the
rootstock bark on one side.
bud wood. This ensures that buds are removed with the
Tie the patch tightly to the tree. Cover all edges of the
bark patch and do not remain attached to the scion wood.
patch and leave the buds exposed (fig. 4). A wax-based budding
Photo: William H. Krueger.
tape is ideal for this purpose because it adheres to itself and
does not have to be tied, secures the buds long enough for them
to heal to the tree, and will stretch and break when the tree
grows and does not have to be removed at a later date. Budding
rubbers or plastic budding tape can also be used. Remove plastic
tape after the buds are healed to avoid constricting the shoot.
Check the buds 2 to 3 weeks after placement; they should
appear to be well healed, green, moist, and well attached to the
rootstock. It may be possible to see callus tissue forming around
the margin of the bud. If the buds have healed, force them to
grow by cutting the limb directly above the new bud (see p. 4).
If the budding was done late in the season (late July or August),
it may be desirable to allow the bud to remain dormant until the
next spring.
Figure 3. Peel back the bark from the rootstock and slip the
bud into place. Photo: William H. Krueger.
3
ANR Publication 8115
PAT C H B U D D I N G L A R G E R T R E E S
Figure 4. Secure the bud with wax-based budding tape. Bud rubbers or plastic budding tape can also be used. Photo: William H.
Krueger.
Figure 5. When patch budding large trees, insert the bud under the
rootstock’s bark to help hold the bud in place. Photo: William H.
Krueger.
Figure 6. Secure patch buds on large trees by wrapping the buds
with string. Photo: William H. Krueger.
While patch budding is more commonly used on smaller trees, it
can be successfully used, with certain adaptations, on larger trees
with scaffold limbs 6 inches (15 cm) or greater in diameter.
One problem when patch budding larger trees is that the
bark of the rootstock is much thicker than the bark of the
scion, making it difficult to ensure adequate contact of the cambial layers to allow the patched bud to heal. One way of overcoming this limitation is to use the bark from the rootstock to
hold the patch in place. To do this, remove the patch from the
scion as described above. With larger limbs it is helpful to use
larger patches, buds cut from branches 1⁄2 inch (1.3 cm) in
diameter or greater. In some cases, it may be desirable to use
buds from 2-year-old growth. Hold the patch on the limb where
the bud is to be placed and cut through the bark of the limb to
be grafted on the sides and top of the bud. The side cuts should
be wide enough to accommodate the patch while leaving a
small open space on one side of the bud to prevent the bud
from buckling and losing cambial contact. Pry up the bark flap
and slip the bud under the bark (fig. 5). Push the patch down
until the top of the patch is even with the top cut on the rootstock. Place a bud every 3 to 5 inches (7.5 to 12.5 cm) around
the limb at the same height on the branch. (This spacing is similar to bud stick spacing in bark grafting.) Secure the buds by
tightly wrapping a piece of twine several times around the limb
(fig. 6). The twine should press the bark flaps to the buds and
hold them in place.
Using bark from the rootstock to hold the bud in place is
generally easier and more successful on smooth-barked limbs
than on older limbs with cracked or fissured bark. This is probably because the smooth bark is more pliable and conforms
more easily to the bud. Thin old, fissured bark by removing the
outer layer of the bark with a knife before inserting the bud.
This leaves the more pliable inner bark, which conforms more
easily to the bud.
Figure 7. Healed patch in a somewhat larger tree 1 to 2 months after placement. Photo: Zachary Heath.
4
ANR Publication 8115
Buds take longer to heal on larger limbs than they do on smaller limbs: 1 month
appears to be the minimum, and it is often best to wait longer before forcing the buds.
After 1 month, remove some of the ties and inspect the buds. If the buds appear to be
healthy and well healed (fig. 7), remove the rootstock limb just above the new buds
to force the buds to grow. Buds can also be forced by girdling the trunk (removing a
strip of bark) just above the inserted bud (fig. 8). The time required for the buds to
heal before forcing may not allow adequate time for sufficient growth to occur before
the end of favorable growing conditions. If the buds are forced too soon, their survival
rate may be reduced. An alternative to forcing the buds the same year is to allow them
to remain dormant for the rest of the season. This allows a long budding window
(easily from May through August) and can result in a higher survival rate, especially
compared to forcing the buds too early during the year they are placed.
The ties and bark flap can be removed after the bud has healed well. They
should be removed within 2 months so that the bark flap does not overgrow the bud.
To remove the bark flap, cut and remove the twine, then cut through the bark flap at
the bottom of the patch and remove it, taking care not to expose the cambium below
the bud.
As with other types of topworking, leave one or two scaffolds on the south side
of the tree to serve as “nurse limbs” to help maintain the root system (fig. 9). The
nurse limbs are normally removed after 1 or 2 years when the buds have made adequate growth.
One drawback to budding larger limbs is the risk that the new shoots will break
off before they are adequately supported by the rootstock. Buds grow very rapidly, and
their new growth can quickly become quite large. This new growth is secured to the
tree only by the new wood that grows under and around the bud. Because of this weak
connection, the new growth may break off. However, if several buds were patched,
enough of them will usually survive to make up for the ones that are lost. The risk of
breaking can be reduced by pruning the tips of the new shoots to stiffen them and
slow their growth, or by tying the new shoots to sticks or lath nailed to the tree.
F O L L O W- U P C A R E
After the buds begin to grow, remove competing buds that sprout below the new buds
to encourage the new buds to grow. Competing buds may need to be removed several
Figure 8. Girdling the limb just above the patch bud forces the bud
to grow. Photo: William H. Krueger.
Figure 9. Retain one or two scaffold branches on the south side of a budded tree to act as nurse limbs. Remove nurse limbs after 1 or 2 years. Photo:
William H. Krueger.
5
ANR Publication 8115
times the first and second seasons. If these buds are not removed, their growth will
outcompete the patched buds and limit their growth.
Although much less problematic than with bark grafts, patch buds should be
watched for infestation by American plum borer (Euzophera semifuneralis), whose larvae feed on the callus tissue that heals the patch to the rootstock. Their presence is
indicated by frass (reddish, sawdustlike fecal material) at the base of the patched
buds. Plum borer feeding can threaten the survival of the new shoots. Additionally,
the new growth from the buds may be damaged by feeding from weevil species,
including the cribrate weevil (Otiorhynchus cribricollis). These nocturnal feeders cause
a characteristic notching of the leaves. Feeding damage on mature trees is normally of
little consequence. However, because feeding damage is normally concentrated on the
lower part of the tree where the buds are located, the buds may be stunted or even
killed. Watch the buds for damage from these or other insects and, if noticed, treat
with a registered insecticide (see UC IPM Pest Management Guidelines: Olive, ANR
Publication 3452).
F O R M O R E I N F O R M AT I O N
You’ll find more information on planting and care of olive trees in the following ANR
products:
Olive Production Manual, UC ANR Publication 3353, 1994.
Propagation of Temperate-Zone Fruit Plants, UC ANR Publication 21103, 1994.
UC IPM Pest Management Guidelines: Olive, ANR Publication 3452, 2002, available
for free downloading from the UC IPM Web site at
http://www.ipm.ucdavis.edu/PMG/selectnewpest.olives.html#INSECTS.
Visit our online catalog at http://anrcatalog.ucdavis.edu. You can also place orders by
mail, phone, or FAX, or request a printed catalog of publications, slide sets, CDROMs and videos from
University of California
Agriculture and Natural Resources
Communication Services
6701 San Pablo Avenue, 2nd Floor
Oakland, California 94608-1239
Telephone: (800) 994-8849 or (510) 642-2431; FAX: (510) 643-5470
E-mail inquiries: [email protected]
An electronic version of this publication is available on the ANR Communication Services Web site
at http://anrcatalog.ucdavis.edu.
Publication 8115
© 2004 by the Regents of the University of California, Division of Agriculture and Natural
Resources. All rights reserved.
The University of California prohibits discrimination against or harassment of any person
employed by or seeking employment with the University on the basis of race, color, national origin, religion, sex, physical or mental disability, medical condition (cancer-related or genetic characteristics), ancestry, marital status, age, sexual orientation, citizenship, or status as a covered
veteran (special disabled veteran, Vietnam-era veteran or any other veteran who served on active
duty during a war or in a campaign or expedition for which a campaign badge has been authorized). University Policy is intended to be consistent with the provisions of applicable State and
Federal laws.
6
ANR Publication 8115
Inquiries regarding the University’s nondiscrimination policies may be directed to the Affirmative
Action/Staff Personnel Services Director, University of California, Agriculture and Natural
Resources, 300 Lakeside Drive, 6th Floor, Oakland, CA 94612-3550 (510) 987-0096. For a free
catalog of other publications, call (800) 994-8849. For help downloading this publication, call
(530) 754-5112.
pr-1/04-SB/CR
ISBN 978-1-60107-294-8
This publication has been anonymously peer reviewed for technical accuracy by University of California
scientists and other qualified professionals. This review process was managed by the ANR Associate
Editor for Pomology, Viticulture, and Subtropical Horticulture.